1. Field of the Invention
The present invention relates to a camera system, particularly to a superior camera system which meets various sufficiently high and wide requirements placed to the camera.
2. Description of the Prior Art
When we think of a camera device for taking a picture, the photographic system as total system can not be disregarded. Waht is called the photographic system here is the combination of the five elements, namely the object system, the projection system, the recording system, the adjusting system and the observation system.
It is well known that each of the above mentioned system makes an important factor for constituting the photographic system. Hereby the object system means the things for making the photographic object, which is generally called the object to be photographed. This includes all of the object field appearing on the picture plane. Further the projection system serves to form the optical image of the above mentioned object system on the next recording system, including the two system, namely the optical system including lenses and the body system including various mechanisms. Then the recording system is the one for recording the optical image formed by means of the above mentioned projection system in a form in accordance with the purpose, whereby in case of the ordinary photographic system the image generally assumes the form of the optical image so as to be visualized, while depending upon the purpose the image assumes, the form of the relief. Further even in case of the visualized image, other light sensing means than the so called photographic light sensitive material participates in many cases so that it is also possible to think of an image system with the recording system as center. The adjusting system means the process for completing the most effective photographic image for the next last observation system out of the recording system, by adding some energy to the fixed image obtained in the above mentioned recording system. Further the observation system means for completing the photographic image obtained through the above mentioned adjusting system as human visual phenomenon.
Hereby the important system for constituting the ordinary camera device is the projection system, whereby the control operation of this projection system has something important to do with the object system, the recording system, the adjusting system and the observation system, being greatly influenced by means of the informations or the fed back informations from these systems. In consequence the camera device often means the above mentioned projection system, whereby it would be essential to establish a total system as effective photographic system, taking the connections with other system sufficiently into consideration, in order to constitute the camera device.
When such a camera device is thought of from the view point of the photographic work on the actual spot, the problem of the operability which has one of the most important connection with the photographer who is the subject of the projection system should be pointed out beside the problem of the optical and the mechanical precision, or of the efficiency.
The projection system, namely the camera device can, as has already been explained, be divided into two systems, namely the optical system and the body system, whereby their efficiencies are different in accordance with the kinds of the camera device. Now in case of the ordinary single reflex camera as one example, the optical system includes the focusing efficiency and the aperture adjusting efficiency while the body system includes the shutter efficiency and the finder efficiency. These functions have an important relation with the operability of the camera device with respect to the aperture value deciding operation, the exposure time deciding operation, the focal distance deciding operation, the framing operation and so on.
Out of the above mentioned operations, the operation for deciding the aperture value and that for deciding the exposure time are mutually connected as the operations for deciding the exposure amount, while they have different effects for deciding the exposure conditions so that it is necessary to operate them, selecting them properly. To explain more in detail at the time of taking a picture the shutter is operated after the focusing operation, the framing operation and the exposure deciding operation, whereby it is general to control the aperture value and the shutter speed in order to control the exposure. However, the original purpose for controlling the aperture value is to decide the object field depth, namely the aperture value should be selected in order to obtain the standing out effect of the main object by making use of the out-focusing effect. On the other hand, the shutter speed should be selected to prevent the vibration of the camera or on the contrary to give a proper movement so as to obtain an emotional picture. Namely at the time of taking a picture it is thought that the aperture value and the shutter speed are the variables to be selected independently from each other.
Now let us think of a camera device consisting of the combination of a lens with a diaphragm mechanism whose F-value varies from F.sub.1 (APEX value: AV=0) to F32 (APEX value: AV=10), namely an optical system, with a body with a shutter mechanism whose shutter time varies from 1 sec. (APEX value: TV=0) to 1/2000 sec. (APEX value: TV=11), namely a body system. Then the control range of the exposure amount covers altogether 22 steps, ranging from the exposure amount EV=0 whereby the F-number is 1, while the shutter time is 1 sec. to the exposure amount EV=21 whereby the F-number is 32, while the shutter time is 1/2000 sec. On the other hand there are 11 steps in the F-numbers while there are 12 steps in the shutter time so that the number of their combination amounts to 132 altogether. Despite of the 132 kinds of the combination, the variation of the exposure amount is summarized into 22 steps as has already been explained, when only the exposure amount is taken into consideration, whereby, however, in the photographic system the aperture value and the shutter time have an efficiency quite independent from each other especially for the photographic image in the observation system so that they have to be selected in a proper way.
On the other hand, the exposure amount is a factor having a very important relation with all of the systems in the photographic system, more particularly in form of the brightness with the object system, in form of the selection of the aperture value and the shutter speed with the projection system, in form of the sensitivity with the recording system, in form of the increase respectively decrease of the sensitivity with the adjustment system and in form of the tone of the photographic image such as high key tone, key tone with the observation system.
In consequence it goes without saying that the exposure amount should be considered in connection with the photographic system as a whole. Now let us consider the projection system, namely the camera device only. In case the exposure amount EV=11 is desired to be obtained, there are 11 combinations of the aperture values with the shutter times as follows: (F1: 1/2000 sec.) (F1.4: 1/1000 sec.) (F2: 1/500 sec.) (F2.8: 1/250 sec.) (F4: 1/125 sec.) (F5.6: 1/60 sec.) (F8: 1/30 sec.) (F11: 1/15 sec.) (F16: 1/8 sec.) (F22: 1/4 sec.) and (F32: 1/2 sec.). Theoretically any one of the above combination gives the same exposure amount, whereby, however, as has already been explained, the aperture value and the shutter time does not work only as the factor for controlling the exposure amount and the aperture value directly acts on the object field depth and the image description while the shutter time directly acts on the description of the object in motion and so on. Although they give the same exposure amount, the combination of F.sub. 1 with 1/2000 sec. gives a photographic effect on the photographic image given by the observation system in a different way from that of F32 with 1/2 sec. when the above mentioned conditions are taken into consideration.
Now let us think of a camera device with the automatic exposure control device, namely an AE (automatic exposure) camera from the above mentioned view point.
The AE camera is a camera device including a mechanism for automatically controlling the aperture value, the shutter time or their combination necessary for obtaining the proper or the desired exposure amount out of the brightness of the object and the sensitivity of the film, whereby in case of the manual camera device it is necessary to take up various photographic conditions, taking various factors into consideration, especially it is necessary for the photographer to select a proper aperture value and a proper exposure time suited for the photographic purpose out of the information of the object brightness measured by means of the exposure meter and the film sensitivity, while in case of the AE camera the photographer can space miscellaneous works at the time of taking a picture so as to enable an efficient and rapid photography so that the camera is becoming widely used.
Further the AE camera can spare complicated operation for obtaining a proper exposure amount by deciding the aperture value and the shutter time in such a manner that the operability of the camera device can be increased largely, while the aperture value and the shutter time to be selected for the same exposure amount are the factors of the characters absolutely different from each other so that much is discussed of the system.
The systems known as the AE camera at present are the following three.
The first one is the so called shutter time priority system for obtaining the proper exposure by way of automatically controlling the aperture value of the photographic lens as the operation result of the brightness of the object, the shutter time optionally decided by the photographer, the film sensitivity, whereby the shutter time, the film sensitivity and so on are given in advance.
The second one is the so called aperture value priority system for obtaining the proper exposure by way of automatically controlling the shutter time as the operation result of the brightness of the object, the aperture value optionally given by the photographer, the film sensitivity and so on whereby the shutter time, the film sensitivity and so on are given in advance.
The third one is the so called program system for obtaining the proper exposure by way of obtaining the necessary exposure amount as the operation result of the object brightness, the film sensitivity and so on so as to select the predetermined combination of the aperture value of the photogaphic lens and the shutter time for obtaining the above mentioned exposure amount, whereby neigher the shutter time nor the aperture value is decided by the photographer.
Each of the above mentioned system has its own features and has been brought into practice while it is also the fact that each of them has its own shortcoming.
In case of the above mentioned first system, namely the shutter speed priority system there is given a freedom that the shutter time can be optionally selected in advance so that in case of the speedy object such as for the snap photography or of the object in motion or of the telephotography in which there is much possibility for unstable manual holding the shorter shutter time can be selected in such a manner that the movement of the object or the unstable manual camera holding can be taken into consideration, while the object field depth has to be subjected to the aperture value of the photographic lens automatically operated in the camera device in accordance with the shutter time set in advance, so that this can not be said to be a proper exposure control system at the time of taking a picture of a landscape or of a still life whereby the object field depth plays an important part in making a picture or at the time of making use of the object field depth.
Further in case of the second system, namely the aperture value priority system quite contrary to the above mentioned first system for the object of the landscape or of the still life or for the object for which the object field depth is desired to be made use of the object field depth can be taken into consideration while the shutter time can not be selected optionally by the photographer so that in case at the time of taking a picture of the object in quick motion with the manually held camera device the slow shutter time is given as the result of the operation control there is a danger that an unwilling photographic result would be obtained, whereby therefore this can not be said to be a proper exposure control system for the object in quick motion or at the time of taking a picture with the manually held camera device or for the object for which the object field depth effect is desired to be obtained.
Further, in case of the above mentioned third system, namely the program system the combination of the aperture value of the photographic lens with the shutter time is decided unconditionally for a brightness of an object, in such a manner that only the proper exposure is taken into consideration so that the photographic conditions can not be selected optionally by the photogaphy. In consequence the above mentioned program system is applied to the simple middle class camera, whereby this is considered to a remarkably effective system because the exposure amount can automatically be selected for a wide range, while for the aperture value priority system AE camera and the shutter time priority system AE camera much is discussed as to the merits and the shortcomings as mentioned above.
On the other hand for the AE camera it can not be disregarded that there are also the following opinions.
Namely in case of the AE camera the shutter time setting dial is at the position equivalent to the aperture value setting ring, whereby in the APEX system series the shutter time TV and the aperture value AV are in the following relations for the exposure amount; EQU EV=TV+AV (1)
so that when the shutter time setting dial is handled the aperture value is varied in order to obtain a certain exposure amount while the aperture setting ring is handled the shutter time is varied. In consequence either the shutter time setting dial or the aperture setting ring is hand the result is the same, namely there is no need for dividing the case into two.
For example the aperture value priority AE camera known at present is surely the aperture value priority AE camera in case the shutter time automatically controlled is not informed of to the photographer at all, whereby in case the shutter time automatically controlled is displayed in the view finder and the exposure is controlled while the eye is put on the view finder, no matter whether the aperture setting ring or the shutter time setting dial is operated the exposure is controlled while the displayed shutter time is observed in such a manner that the effect is same as in case the shutter time setting dial is handled and the camera can be considered to be a shutter time priority AE camera in this meaning.
Namely the aperture value priority system AE camera and the shutter time priority system AE camera are reversible in their position depending upon how to use and how to think.
To summarize the above, the aperture value of the photographic lens and the shutter time are the factors very important for deciding the exposure amount so that when the automatic exposure control efficiency is accorded to the camera device it is necessary to treat the aperture value and the shutter time equally. This is a problem to be especially thought over because the reason for according the automatic exposure efficiency to the camera device is not only for simplification of the camera handling but also for increasing snap photographic efficiency as well as for allowing the photographer to concentrate himself more on the framing at the time of the camera handling.
Further before discusing about the exposure amount, let us consider two systems, namely the object system and the recording system between which the camera device as the projection system is located.
At the time of taking a picture it is necessary for the object system, namely the object field to have its own brightness, called the object brightness and represented BV in APEX system series. Further the recording system, for example the photosensitive film has a sensibility, called the film speed normally represented ASA by SV in the APEX system series.
As is well known, in the APEX system series the object brightness BV and the film speed SV are the factors for deciding the exposure amount EV in accordance with the following relation EQU BV+SV=EV (2)
Hereby the upper and the lower limit of the EV range settable in the camera device, namely in the projection system, can be made infinite by making the shutter time infinitely long or by providing at the photographic lens for attenuating the light, whereby from the view point of the proper exposure condition there must be the limit.
In consequence, at the time of taking a picture of an object field with the low brightness, namely the BV value is low while the exposure amount is let to be an amount to be decided by the combination of the aperture value with the shutter time for giving a proper exposure condition, it is sufficient to make the film speed SV larger as is clear from the relation (2). On the other hand at the time of taking an object field with the high brightness, naturally it is sufficient to make the film speed SV smaller. This is an important role in the recording system of the photographic system, while, seen from the side of the camera device, the recording system can only participate in the film support, the film exchange or the film feeding and not in the alternation of the sensitivity. The only one that is possible is to prepare a film with ultra high sensitivity and to put film with various permiability selectively into the optical path of the projection system so as to alter the sensitivity of the film in an equivalent way, whereby with the present technical level there is a limit in raising the sensitivity of the film so that it is not easy to apply the above method.
On the other hand, when it is desired to obtain a constant exposure amount while the film sensitivity SV is let to be constant, it is necessary to alter the brightness of the object, which is the well known lighting.
Although various methods for the lighting can be thought of, now let us take up the speed light used most generally now in connection with the camera device.
The intensity of the light amount of the speed light device is called the guide number, whereby generally the aperture value of the lens is decided out of the distance up to the object and the above mentioned guide number. However, quite recently it is in many cases tried to obtain the proper exposure amount automatically even at the time of taking a picture with the speed light device, whereby a system in accordance with which the light reflected from the object field is detected so as to stop the lighting as soon as the amount of the reflected light reaches a certain determined value or the guide number is variable has recently been brought into practice in order that the application of the camera device is enlarged while the freedom for framing is increased. Although such a speed light device constitutes the object system in the photographic system, it is necessary that the speed light device should operate in close connection with the camera device as the projection system because its lightening time is remarkably short, whereby such a device as never disturbs the operability of the camera device nor decreases the freedom of the framing by the photographer is especially desired.
Below the framing operation and the focusing operation will be discussed among the camera operation.
It is general that with the exception of special cases the framing operation as well as the focusing operation is carried out through the view finder at the time of operating the camera device. Hereby the most basic effect of the so called view finder is to allow the photographer to confirm the image of the object to be projected on the film plane as the view finder image, namely to decide the framing at the time of taking a picture. However, at present it is also general to make use of the view finder as the detector of the focusing of the object.
Further in case of the single reflex camera the efficiency for confirming the out-focusing state of the picture plane as the whole is added, while in case of the camera with a built in light measuring mechanism the element for confirming the measured light amount or the light measuring part is added.
As mentioned above the view finder plays an important part in the camera handling and can be said to have an important relation with the operability of the camera, for the most of the camera operation including the framing and the focussing operation as the basic operation is carried out through the view finder.
In consequence the information centralizing view finder has become widely adopted in such a manner that the photographer can obtain all of the photographic informations through the view finder, whereby these information have to be displayed in a limited space so that the easiness of the observation and the confirmation of the informations is required.
Further the application of the camera device has been extended into the range of the low brightness so that it has become necessary that the informations can be confirmed even in the dark place in the view finder just in the same way as in the bright place.
Among the camera operation, the framing operation and the focusing operation have a close connection with the portability of the camera body and the operability of the parts. Namely at the time of taking a picture it is necessary that the framing is decided through the view finder while the camera body is being held in the hands, while the focusing is carried out by operating the distance ring of the lens and the shutter is released at the desired time point after the operation for deciding the exposure and others, so that it is necessary to arrange the parts in a rational way so as not to prevent the operability of other parts. Although at times this is restricted connected with the mechanical arrangement of the camera device, the improvement of the operability is a problem to be treated with the special case because the subject in the projection system in the photographic system is the photographer.
To speak more particularly as to the operability, the projection system serves to fix a certain moment in the recording system so that it is essential that an absolute counter-measures against the misoperation or the mishandling should be carried out.
As mentioned above, the operability of the camera device can be largely improved by organically combining the basic operations such as the operation for deciding the exposure, the framing operation and the focusing operation with other auxiliary operation.
In consequence what is required for the camera device as the projection system constituting a large system as the photographic system is to constitute a large sub-system capable of realizing the largest efficiency of the projection system basing upon the close connection with other system, whereby for example the automatic exposure control should be realized in such a manner that the efficiency of every parts of the camera device can alway be realized in a sufficient way, while all the other auxiliary mechanism should be able to operate in the best way.
Thus the view point of system has become necessary for the camera device, whereby a new demand takes place for a new camera system capable of meeting the requirement of the system in the total system as the photographic system.